My book is full of questions every mildly-educated American SHOULD be able to answer—but often can't. Prior to publication, we ran all the questions past a test audience to see how many people answered each one correctly. Those stats are included in the book, so you can see, on a question-by-question basis, exactly how poorly you stack up against your fellow countrymen. Plus each answer comes with a rip-roaring Fun Fact. For Mental Floss, I'll be taking the best facts from the book and exploring them here in greater depth.

Today's question: John F. Kennedy and Abraham Lincoln were assassinated while in office. But so were two other U.S. Presidents. Can you name either one?

Answers and the stupid reasons they passed away revealed after the jump.

Answer: James A. Garfield and William McKinley. (If you got this wrong, you are dumber than 48% of America.)

The Scoop: After only four months in office, President Garfield was shot in the back while waiting for a train. Modern day experts pretty much agree Garfield's gunshot wounds shouldn't have killed him. If only his doctors had gotten that memo. This was in 1881, back before anyone understood the correlation between germs and disease, so Garfield's doctors stuck unsterilized instruments and even their dirty fingers into the president's body, poking around vainly to find the bullet. What began as a three-inch-deep wound grew into a 20-inch long gash that stretched from Garfield's ribs to his groin. At one point, Alexander Graham Bell even showed up with an early metal detector to try to find the bullet. To his puzzlement, the machine malfunctioned. That probably had something to do with the fact that Garfield was laying on a metal bed—yet another new innovation at that time—and no one thought of mentioning this fact to Graham Bell. Oops. The president went on to die of blood poisoning after 80 days of agony.

Fast forward 20 years to 1901 when McKinley got plugged at the Pan-American Exposition. As the president lay in the hospital on the exposition grounds, doctors were once again unable to find and remove the bullet. This time there was even an experimental X-ray machine on site for the expo—but for some reason no one thought to use it on McKinley.
Thus America lost its third commander in chief in less than 40 years to an assassin's bullet (Lincoln had died back in 1865). Taking the hint, Congress decided that the president should have full time bodyguards. That's when the Secret Service took on the task.
Missed yesterday's column? Check out Adam's terrific post on the strange beginnings to the Civil War here.